From: Jan Beulich <jbeulich@suse.com>
To: Chao Gao <chao.gao@intel.com>
Cc: "Stefano Stabellini" <sstabellini@kernel.org>,
qemu-devel@nongnu.org, "Paul Durrant" <paul.durrant@citrix.com>,
"Anthony Perard" <anthony.perard@citrix.com>,
xen-devel@lists.xenproject.org,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Qemu-devel] [RFC Patch] xen/pt: Emulate FLR capability
Date: Thu, 29 Aug 2019 12:03:44 +0200 [thread overview]
Message-ID: <131d5f04-7ef9-9a2b-3009-2a93587186ef@suse.com> (raw)
In-Reply-To: <1567069347-22841-1-git-send-email-chao.gao@intel.com>
On 29.08.2019 11:02, Chao Gao wrote:
> Currently, for a HVM on Xen, no reset method is virtualized. So in a VM's
> perspective, assigned devices cannot be reset. But some devices rely on PCI
> reset to recover from hardware hangs. When being assigned to a VM, those
> devices cannot be reset and won't work any longer if a hardware hang occurs.
> We have to reboot VM to trigger PCI reset on host to recover the device.
Did you consider a hot-unplug, reset (by host), hot-plug cycle instead?
> +static int xen_pt_devctl_reg_write(XenPCIPassthroughState *s,
> + XenPTReg *cfg_entry, uint16_t *val,
> + uint16_t dev_value, uint16_t valid_mask)
> +{
> + if (s->real_device.is_resetable && (*val & PCI_EXP_DEVCTL_BCR_FLR)) {
> + xen_pt_reset(s);
> + }
> + return xen_pt_word_reg_write(s, cfg_entry, val, dev_value, valid_mask);
I think you also need to clear the bit before handing on the request,
such that reads will always observe it clear.
Jan
next prev parent reply other threads:[~2019-08-29 10:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-29 9:02 [Qemu-devel] [RFC Patch] xen/pt: Emulate FLR capability Chao Gao
2019-08-29 10:03 ` Jan Beulich [this message]
2019-08-29 15:22 ` Chao Gao
2019-08-29 10:21 ` Roger Pau Monné
2019-09-06 9:01 ` Chao Gao
2019-09-06 9:20 ` Paul Durrant
2019-09-06 10:28 ` Roger Pau Monné
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